System and method for removing sulfur from fuel gas streams

Abstract

A system for removing sulfur compounds from a gaseous stream includes an adsorption zone comprising a first fluidized bed comprising a sulfur adsorption material configured to receive a fuel gas stream comprising sulfur compounds and to adsorb and remove the sulfur compounds from the fuel gas stream. The system is configured to generate a product stream substantially free of sulfur and a saturated sulfur adsorption material. The system further includes a regeneration zone comprising a second fluidized bed configured to receive an oxidant and steam to regenerate the saturated sulfur adsorption material. The adsorption zone and regeneration zone are in direct fluid communication.

1 . A system for removing sulfur compounds from a gaseous stream comprising:
 an adsorption zone comprising a first fluidized bed comprising a sulfur adsorption material configured to receive a fuel gas stream comprising sulfur compounds and to adsorb and remove said sulfur compounds from said fuel gas stream to generate a product stream substantially free of sulfur and a saturated sulfur adsorption material; and   a regeneration zone comprising a second fluidized bed configured to receive an oxidant and steam to regenerate said saturated sulfur adsorption material;   wherein said adsorption zone and regeneration zone are in direct fluid communication.   
   
   
       2 . The system of  claim 1 , wherein said sulfur adsorption material comprises zinc oxide and optionally iron oxide. 
   
   
       3 . The system of  claim 1 , wherein said sulfur compound comprises hydrogen sulfide (H 2 S) and carbonyl sulfide (COS). 
   
   
       4 . The system of  claim 1 , wherein said adsorption zone operates at a temperature of about 150 Deg. C. to about 450 Deg. C. 
   
   
       5 . The system of  claim 1 , wherein said first fluidized bed comprises a catalyst to catalyze at least one of a water-gas-shift reaction or a steam reforming reaction. 
   
   
       6 . The system in  claim 1 , wherein said first fluidized bed further comprises a CO 2  adsorption material. 
   
   
       7 . The system in  claim 6 , wherein said CO 2  adsorption material is a metal oxide. 
   
   
       8 . The system in  claim 7 , wherein said CO 2  adsorption material comprises calcium oxide (CaO), magnesium oxide (MgO) or combinations thereof. 
   
   
       9 . The system of  claim 1 , wherein said sulfur adsorption material comprises at least one metal selected from the group consisting of Zn, Mg, Mo, Mn, Fe, Cr, Cu Co, Ce, Ni and combinations thereof. 
   
   
       10 . The system of  claim 5 , wherein said catalyst comprises at least one catalytically active metal selected from the group consisting of Rh, Pt, Pd, Ru, Ir, Re, Os and combinations thereof. 
   
   
       11 . The system of  claim 1 , wherein said sulfur adsorption material is configured to perform at least one function selected from the group consisting of sulfur adsorption function, CO 2  adsorption function, water-gas-shift function and/or steam reforming function and combinations thereof. 
   
   
       12 . The system of  claim 1 , wherein said sulfur adsorption material is produced by a spry-drying process followed by calcination at the temperature range of about 700 Deg. C. to about 900 Deg. C. 
   
   
       13 . The system of  claim 6 , wherein particles of said sulfur adsorption material is in the range of about 10 microns to about 400 microns. 
   
   
       14 . The system of  claim 6 , wherein particles of said sulfur adsorption material is in the range of about 40 microns to about 250 microns. 
   
   
       15 . The system of  claim 5 , wherein said catalyst is configured to facilitate a water gas shift reaction to convert carbon monoxide (CO) to produce hydrogen (H 2 ), and carbon dioxide (CO2). 
   
   
       16 . The system of  claim 1 , wherein said fuel gas is selected from the group consisting of syngas, natural gas, methane, naphtha, butane, propane, diesel, kerosene, an aviation fuel, syngas from gasification of coal, petroleum coke, bio-mass, waste, gas oil, crude oil, an oxygenated hydrocarbon feedstock, and mixtures thereof. 
   
   
       17 . The system of  claim 1 , wherein said saturated sulfur adsorption material is introduced into said regeneration zone through gravity flow. 
   
   
       18 . The system of  claim 1 , wherein said regeneration zone comprises a riser reactor. 
   
   
       19 . The system of  claim 1 , wherein said system further comprises a dense third fluidized bed in fluid communication with said first and second fluidize bed. 
   
   
       20 . The system of  claim 19 , wherein said third fluidized bed is configured to receive steam. 
   
   
       21 . The system of  claim 1  further comprising at least one first solid separation unit in fluid communication with said adsorption zone and a second solid separation unit in fluid communication with said regeneration zone. 
   
   
       22 . The system of  claim 21 , said first and second solid separation units comprise a two-stage closed cyclone configured to separate particles of said sulfur adsorption material to minimize the loss of said sulfur adsorption material. 
   
   
       23 . The system of  claim 1 , wherein said oxidant is selected from air, steam, oxygen depleted air, oxygen enriched air and mixture of air and steam. 
   
   
       24 . The system of  claim 1 , wherein said fuel gas is synthesis gas. 
   
   
       25 . The system of  24 , wherein said synthesis gas is produced from gasification of solid and/or liquid fuels, such as coal, biomass, waste, oil and fuels derived from them. 
   
   
       26 . The system of  claim 24 , wherein said synthesis gas is used in a power generation unit, coal to liquid plant, a hydrogen generation unit or combinations thereof. 
   
   
       27 . A system for producing a synthesis gas comprising;
 a gasifier configured to receive a solid or liquid fuel and an oxidant to produce a synthesis gas comprising sulfur compounds;   a system for removing sulfur compounds from a gaseous stream comprising:
 an adsorption zone comprising a first fluidized bed comprising a sulfur adsorption material configured to receive a fuel gas stream comprising sulfur compounds and to adsorb and remove said sulfur compounds from said fuel gas stream to generate a product stream substantially free of sulfur and a saturated sulfur adsorption material; and 
 a regeneration zone comprising a second fluidized bed configured to receive an oxidant and steam to regenerate said saturated sulfur adsorption material; 
 wherein said adsorption zone and regeneration zone are in direct fluid communication. 
   
   
   
       28 . The system of  claim 27 , wherein said synthesis gas is produced from gasification of solid or liquid fuels selected from the group consisting of coal, biomass, waste and oil. 
   
   
       29 . A method for removing sulfur compounds from a gaseous stream comprising:
 adsorbing said sulfur compounds in an adsorption zone comprising a first fluidized bed comprising a sulfur adsorption material configured to receive an fuel gas stream and producing a product stream substantially free of sulfur and a saturated sulfur adsorption material; and   introducing an oxidant and said sulfur adsorption material from said adsorption zone into a regeneration zone comprising a second fluidized bed and regenerating said saturated sulfur adsorption material;   
     wherein said adsorption zone and regeneration zone are in direct fluid communication. 
   
   
       30 . A system for removing pollutants from a gaseous stream comprising:
 an adsorption zone comprising a first fluidized bed comprising an adsorption material configured to receive a fuel gas stream comprising said pollutants and to adsorb and remove said pollutants from said fuel gas stream to generate a product stream substantially free of pollutants and a saturated adsorption material; and   a regeneration zone comprising a second fluidized bed configured to receive an oxidant and steam to regenerate said saturated adsorption material;   wherein said adsorption zone and regeneration zone are in direct fluid communication and said pollutants comprises at least one of sulfur compounds, chlorine (Cl), ammonia (NH 3 ), mercury (Hg), arsenic (As), selenium (Se), cadmium (Cd) and combinations thereof.